Illuminant for incandescent electric lamps and process of making



No. 6|6,27e. Patented Dec. 20, I898. 0. m. THOWLESS.

ILLUMINANT FDR INCANDESCENT ELECTRIC LAMPS AND PROCESS vOF MAKING. (Application filed Jan. 31, 1896.)

(No Model.)

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. a si1bject of the Queen of Great Britain, re- .siding at Newark, county of Essex, and State of New Jersey, havcinvented certain new and UNITED STATES PATENT I OFFICE.

ORLANDO M. THO\VLESS, 'OF NElVrlltK, NElV JERSEY.

ILLUMINANT FOR INCANDESCENT ELECTRIC LAMPS AND PROCESS OF MAKING.

SPECIFICATION forming part of Letters Patent NO. 616,276, dated December 20, 1898.

Application filed January 31, 1896. Serial No. 577,513. (No model.)

T rtll wit-nut if may lflllllfl'll.

Be it known that I, ORLANDO M. 'inowLE-ss,

useful Improvements in Illuminants for Incandescent Electric Lamps and in Processes of Making the Same, of which the'following is a specification.

My invention relates to the construction of the illuminating portion of an incandescent electric lamp. 7

The object of my'irivent-ion is to provide an illuminant which will yield a greater amount of light than is ordinarily obtained from an incandescent filament of the usual construction by the consumption of a given amount of electrical ener y.

a .My invention comprises a new process or method of operation and a new product produced thereby. This new product may be generally described as an illuminant for incandescent electric lamps consisting of a filament inclosed within a sheath or covering of material possessing the property of illuurinating readily by the action of an electric current. The material may be one of the class having the general characteristics of an oxid of thorium, zirconium, yttrium, or lanthanum or some other metallic oxids of the same general characteristics, and the new process consists of the novel method of obtaining the product, which is accomplished by preparing on the filament a combustible mat-erial-Psuch, for instance, as cotton-impregnated with the salts of one or more metals, then destroying the combustible material and reducing the metallic salts to their corresponding metallic oxids, thereby forming on the filament a sheath-or cover of metallic oxid. This method .and its modifications are hereinafter more fully described.

character through a sheathing or tube of woven fibrous material-.such, for instance, as cotton. This-is then impregnated wit-h a salt, in solution, of thorium or zirconium, yttrium or lanthanum, or some other suitable salt the oxid of which possesses in ahigh degree the property of illuminating readily and is capable of withstanding an intense heat. The nitrate'of thorium, for example, gives excellent results. The strength of the solution may be varied as required for the purpose of giving to the completed filament agreatcr or less amount ofccating. The filament, with its'coating, is then dried, and the fibrous structural coating or tube is then removed by heat-as, for instance, by placing it in a furnace or even, where suflicient heat may be applied to destroy the cotton or other fiber and reduce the salt to an oxid, thus leaving a coating of the oxid of the metal-in close proximity to the filament. After the filament has thus been prepared it is then in condition to be placed in the usual form of vacuumchamber or lamp-globe and exhausted in the usual well-known. manner.

Instead of threading the filament through the covering of fibrous material the latter may be woven upon or otherwise applied to the filament. I

The sheathing, tube, or covering may be soaked in the solution of the metallic salt before it is applied to the filament, and, indeed,

the cotton or other material of which the cover is to be formed may be treated with metallic salts before it is woven or otherwise shaped.

A lamp thus made is found to be durable and ci'ficient, and the light-giving properties of the filament are materially enhanced by the presence of the coating. The coating adheres more orless closely to the surface of the filament, and this intimate relation of the metallic oxid with the filament secures stability for the entire structure. This method of applying the coating permits the necessary expansion and contraction of the filament without causing the coating to be broken.

Various diilcrent salts of the metals may be applied in practice.

A modification in the process of applying the coating to thefilamcnt consists in first impregnating one coating in the manner a1- ready described and afterward forming one or more additional coatings of either the'same or of difierent oxids in essentially the same manner. K I

Another'modification consists in impreghating the coverings of the filament with salts of two or more diflferent metals before the preliminaryheatin g, and this may be done either by soaking the filament and its fibrous covering in the salts of the metals successively or in a mixture of two or more of such salts simultaneously, 'or after one such coating has been so treated another fibrous tube or covering may be-superposed and the treat- -ment repeated. The fibrous covering is then destroyed and the salts reduced to their reis represented at C, Fig. 2, and the parts d d represent leading-in wires for supportingthe completed illuminant e.

I claim as my invention- 1.' The hereinbefore-described method of applying a coating. of refractory material to a filament for incandescent electric lamps, which consists in first applying a covering of readily-combustible material to the surface of the filament, impregnating the same with a salt of thorium or other metal, and removing the covering of combustible material by heat or decomposition.

2. The herein before-described method of preparing incandescent electric lamp fila- A suitable inclosing bulb ments whiclr'eonsists in incasing the length of the filament in a continuous woven sheathing,'impregnating the same with a metallic salt, and removing the coating of woven material by heat, and reducing theinetallic salt to a metallic oxid, substantially as described.

3. The hereinbefore-described method of preparing incandescing conductors for electric lamps which consists in incasing a filament in a covering of combustible material impregnated with a metallic salt, and removing such combustible material by heat or decomposition and reducing the metallic salt to a metallic oxid.

'4. The hereinbefore-described method of preparing conductors for incandescing electric lamps, which consists .in incasing a filament in a covering of combustible material impregnated with two or more metallic salts, destroying such combustible material, and reducing the salts of the metals to the corresponding metallic oxids.

5. The method of preparing conductors for incandescing electriclamps whichconsi'sts in incasing a filament in a covering of combustible material, impregnatedwith a metallic salt, subjecting the same to a bath of one or more other metallic salts, and then destroy ing the covering of combustible material.

6. An illuminant for incandescent electric lamps consisting of a carbon filament and a surrounding sheath or covering of oxid or other compound of thorium.

7. An illuminant for incandescent electric lamps consistingof a filament, a surrounding sheath or covering of oxid or other compound of-thorium,orits equivalent,and an exhausted bulb containing the same.

In testimony whereof I have hereunto subscribed my name this 24th day of January, A. 1896.

' ORLANDO M. THOWLESS.

Witnesses:

' H. A. CROOKS,

-W. D. UPTEGRAF'F. 

